As opposed to the satiric social commentary of his later magnum opus, Stranger in a Strange Land (1961), Heinlein’s The Door into Summer falls into the vat of sentimentality. One critic at the time of publication noted that the book reveals myriad “gadgets-to-be.” Readers who realize that Heinlein’s “future” is “now” or has passed without those gadgets having come to be are left with only the plot of the novel, which revolves around a maudlin, self-serving, and pathetic protagonist. The only character of any real interest is the cat.
The problem may lie with the brevity of the work. Readers have little time to engage with the future before the plot yanks them back to the past, then thrusts them forward again. Vertigo replaces interest in the lives of any of the characters. Additionally, there is a rending of belief for even the most inveterate fans of science fiction. The most far-fetched portion of the plot concerns the protagonist repeating the time travel process primarily to procure the love of an eleven-year-old child.
The saving grace in the work lies with the often unexpected use of humor. For example, the time machine inventor explains that the only test on a human was unsuccessful: Leonard Vincent, a twenty-first century draftsman and artist, was transported back to the fifteenth century and did not return. Daniel’s time traveling excursion, in another humorous incident, plunges him, fully dressed, from the sky into the center of a nudist colony.
The Door into Summer shows the shaping of themes that would predominate in Heinlein’s later work. Underlying the basically bland plot structure is a hero’s escape from a stifling maze into boundless freedom, coupled with a reverence for intellect, survival, and joie de vivre.
For all of his love of science fiction and technology, Heinlein’s view of the future is dark and bleak, and his reaction to progress is often cynical. In his “futuristic” 1970, inventors are products of corporations, and in his 2000, the world is monopolized by zombie recruiters, rampant overpopulation, and bureaucratic stifling.